It is widely recognized in horse racing that there is a relationship between lameness in horses and the type of track or other surface upon which the horse is running. Studies have been conducted which show that the greatest risk of lameness occurs in the left front leg of a horse going around the relatively sharp turns used in conventional horse racing tracks. It has further been discovered that horse tracks having more gradual curves and embanked track surfaces on the corners help to further reduce the risk of lameness. Other factors such as the resiliency of the track surface also affect the likelihood of lameness developing.
It has also been recognized by equestrians that variations in the properties of track surfaces can have a significant effect on racing times. Resiliency and other factors of track performance may also have significant effects on the effectiveness and efficiency of different types of track surfaces in strengthening horses.
In the veterinary and horse training field it has further been recognized that information on the types and amounts of forces applied by the horse to the track are significant in better understanding of lameness, equine locomotion, and track performance. Previous researchers have utilized force detecting plates which are relatively easily installed in a track. A horse is run over the force plate and the amount of force applied by the horse's hoof is recorded. Use of force plates to detect and analyze locomotor forces has been found less than satisfactory. The relatively greater rigidity and hardness of the plate as compared to the track surface makes it uncomfortable for the horse to strike his hoof upon the surface during gaits faster than a trot. Accordingly, horses typically avoid force plates as soon as they have learned the position during experimental trials. Force plates are also limited by their inability to measure forces applied during successive strides. This prevents careful analysis of force variations which may be due to natural fluctuations in the animal's gait. Force plates have also been found undesirable because of the relative difficulty in achieving accurate results when the horse or other hoofed animal runs over the plate at a fast gait.
The research team of Frederick and Henderson sought to overcome some of the limitations of force plates using a specifically designed force sensing horseshoe which was attached to a horse's hoof. The Frederick and Henderson horseshoe used a "hoof plate" which is connected to the hoof of the animal. A plurality of strain gauge washers were positioned between the hoof plate and a force plate using bolts. The force plate contacted the ground during running of the horse. Bolts connecting the force plate and hoof plate together were torqued to provide a preload on the washer-shaped strain gauge transducers through which the bolts extended.
The Frederick and Henderson force measuring horseshoe is disadvantaged by its use of two relatively rigid and heavy plates weighing in excess of normal horseshoes. The use of two plates spaced apart by strain gauge transducers also has a substantially greater height than a typical horseshoe. Scientific studies have shown that increased height and weight of horseshoes substantially affects the locomotion pattern of a horse using such shoes. Accordingly, it is not possible to accurately assess the forces applied by a horse or other hoofed animal during actual running conditions. Variations in the gait caused by relatively heavy or thick horseshoes also alters the anatomical motion of the horse's leg, thereby reducing the significance of studies using high speed photography.
The present invention provides animal hoof force detection systems using relatively lightweight shoe and transducer structures which can be used to reliably indicate the forces applied by hooves during free animal locomotion. The systems are advantageously carried on the animal so that no tether or cable impedes the range or type of surface over which the system can be used. The system further allows substantially continuous monitoring of one or more of the animal's hooves in order to identify the timing and magnitude of the ground contact forces applied by the animals hooves. Other advantages and objects of this invention will be apparent from the description given herein and the expertise of one of ordinary skill in the art.